The proposed research involves two general lines of investigations designed to characterize the interrelationship of prostaglandins, the renin angiotensin system and salt and water equilibrium. The first line of research attempts to define the role of prostaglandins in the development of experimental renal hypertension. This goal will be achieved by examining the effect of the administration of blockers of prostaglandin synthesis on 1) blood pressure, 2) the components of the renin-angiotensin-aldosterone system and 3) the excretory function of the kidney in a) normal rabbit and b) in two different models of rabbit renal hypertension, under basal conditions and after changes in extracellular fluid volume induced by high and low sodium dietary intake. The second line of research aims 1) to define whether the blockade of renin release induced by indomethacin is exerted directly by this drug or indirectly through the blockade of prostaglandins and 2) to test the relative potency of other anti-inflammatory drugs such as meclofenamate, aspirin, and eicosatetraenoic acid in inhibiting the release of renin.